[Widening of the sub-acromial space using a wedge osteotomy of the scapular spine. Anatomical bases, measurements on the preparation, studies of the kinematics of the acromion movements on a computer model].

We describe the theoretical principles of a new kind of decompression of subacromial impingement syndrome by means of a wedge osteotomy at the transition between acromion and spine of the scapula. The operation on cadaver bone and the simulation of acromion movement in a computer model demonstrate an increase of subacromial space more than 1 cm after wedge excision with cranial base of 5 mm and ventral base of 3 mm. After the excision of an anterior based wedge the resection of the coracoacromial ligament is not necessary. An angle between 50 and 60 degrees from mediocranial to laterocaudal referred to the transverse plane has been calculated as optimal. We regard the sparing of the abducting parts of deltoid muscle, the better approach to the cuff with the possibility to mobilize the supraspinate muscle in cases of greater cuff-tears and the possibility to obtain a smooth undersurface of the acromion as further advantages of this procedure. Further biomechanic experiments will be necessary to optimize osteosynthesis.